Relationship between arterial, mixed venous, and internal jugular carboxyhemoglobin concentrations at low, medium, and high concentrations in a piglet model of carbon monoxide toxicity

Objective: This study tested the hypothesis that mixed venous carboxyhemogl obin concentrations (V-COHb) and internal jugular carhoxyhemoglobin concent rations (I-COHb) accurately predict arterial carboxyhemoglobin concentratio ns (A-COHb). In addition, this study tested the hypothesis that there is a high correlation at low (COHb, 0% to 10%), moderate (COHb, >10% to 40%), an d high (COHb, >40%) concentrations between V-COHb, I-GOHb, and A-COHb. Design: The study was a prospective comparison of A-GOHb, V-COHb, and I-COH b concentrations in piglets exposed to increasing concentrations of carbon monoxide over 6 hrs to achieve a concentration of greater than or equal to 60% COHb. Carboxyhemoglobin measurements were evaluated by analysis of vari ance and correlation analysis. Agreement between V-COHb and A-COHb concentr ations was examined by using a plot of arteriovenous differences against th e mean of the two measurements. Intervention: We simultaneously sampled arterial, mixed ve-nous, and intern al jugular blood every 30 mins over the 6-hr study period. Results: Two hundred fifty arterial and mixed venous COHb concentrations we re obtained, and 214 internal jugular COHb concentrations were obtained. On e hundred additional arterial, mixed venous, internal jugular, and peripher al COHb concentrations were obtained. Correlation between samples at each c oncentration revealed r(2) greater than or equal to .94. Conclusion: Venous COHb concentrations predict arterial COHb concentrations with a high degree of accuracy and are correlated at low, moderate, and hi gh concentrations of carbon monoxide exposure. Arterial or venous samples c an be used to accurately measure COHb concentrations.